"I am a proud Illinoisan today," Lt. Gov. Sheila Simon said Wednesday, kicking off a line of speakers celebrating the signing. "Thanks to everyone in the state of Illinois for making this a land we can all be proud of. It's time to stop planning rallies and start planning weddings."

Quinn took that sentiment a step further, urging other states to follow suit with marriage equality legislation.

"We understand in our state that part of our unfinished business is to help other states in the United States achieve marriage equality," Quinn said. "We want to have a new birth of freedom across America, and love is not relegated to second-class citizen status."

Bill sponsor Rep. Greg Harris received an especially thunderous round of applause and a standing ovation. He thanked a long list of supporters, from politicians and families to church leaders and businesses that helped make the legislation possible.

"It has been a long and painful wait for many people," Attorney General Lisa Madigan said. "At its heart marriage equality is about the fundamentals of American principles of fairness and freedom, and it is about families."

Illinois' law takes effect June 1, 2014, and is expected to increase business and tourism spending in the state. A 2013 study by UCLA's The Williams Institute said that allowing same-sex couples to marry in Illinois would generate up to $103 million in new spending in the first three years. The Illinois Office of Tourism has already beefed up its website to promote gay-friendly spots in Illinois.

Cook County Clerk David Orr said his offices will be open on June 1, a Sunday, so gay couples can get their marriage licenses. In central Illinois, Champaign County Clerk Gordy Hulten said his office will be open, and in southwestern Illinois, Madison County Clerk Debra Ming-Mendoza said the office will open to issue marriage licenses June 2.

Quinn signed civil union legislation into law in 2011. Since then, the governor's office said more than 6,000 Illinois couples have joined in a civil union. The bulk of them have been in Cook County.